1. Field of the Invention
The present invention relates to an image sensing device, and more particularly, to a pixel designed to increase a speed at which charges are transmitted, an image sensor with a wide extended dynamic range, and an image sensing device including the image sensor.
2. Description of the Related Art
An image sensor includes a plurality of pixels that receive external light and produce electric charges, and converts an optical image into an electrical signal.
FIG. 1 illustrates a semiconductor device 101 in which pixels of a conventional charge coupling device (CCD) type imaging device are formed. Referring to FIG. 1, the semiconductor device 101 includes a plurality of pixels 111, a plurality of vertical transmission lines 161, and a single horizontal transmission line 171.
Each of the pixels 111 includes a photo diode area 121, a transmission gate area 131 formed on one side of the photo diode area 121, a vertical transmission area 141 formed adjacent to the photo diode area 121, and a channel stop area 151 formed on the three remaining sides of the photo diode area 121.
The vertical transmission lines 161 each include vertical transmission areas 141 and are all connected to the horizontal transmission line 171.
In the convention pixel 111, the photo diode area 121 has a rectangular shape, and the transmission gate area 131 is formed on a portion of a side of the photo diode area 121. Because the shape of the photo diode area 121 is rectangular, charges generated in the photo diode area 121 are collected at corners of the rectangular photo diode area 121. The collection of the charges at the corners of the rectangular photo diode area 121 delays transmission of the charges generated in the pixels 111 to the horizontal transmission line 171 via the vertical transmission lines 161. This delayed transmission causes a reduction of the speed of imaging by an imaging device.
In addition, since light-receiving elements included in a conventional image sensor receive identical amounts of light, it is difficult for the conventional image sensor to have a high dynamic range. In a current situation, an image sensing device must use two or more image sensors to obtain a high dynamic range. However, the use of two or more image sensors increases the costs for manufacturing the image sensing device, resulting in a high-priced image sensing device.